Selected Reaction Monitoring Scan Type; Scan Mass-To-Charge Ratio Ranges; Data Types - Thermo Scientific TSQ Endura Hardware Manual

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Scan Parameters

Scan Mass-To-Charge Ratio Ranges

Selected Reaction Monitoring Scan Type

Scan Mass-To-Charge Ratio Ranges

Data Types

20 TSQ Endura and TSQ Quantiva Hardware Manual
Selected reaction monitoring (SRM) monitors a particular transition or set of transitions, such
as the fragmentation of an ion or the loss of a neutral moiety.
SRM monitors a limited number of precursor or product ion pairs. In product-like
experiments, the mass spectrometer selects a precursor ion as usual, but generally it only
monitors one product ion. SRM experiments are normally conducted with the product scan
mode.
As does SIM, SRM provides for the very rapid analysis of trace components in complex
mixtures. However, because SRM selects two sets of ions, it obtains specificity that is much
greater than what SIM can obtain. Any interfering compound would have to form an ion
source product (precursor ion) of the same mass-to-charge ratio as the selected precursor ion
from the target compound. Furthermore, that precursor ion would have to fragment to form a
product ion of the same mass-to-charge ratio as the selected product ion from the target
compound.
The TSQ Endura MS can operate in a mass-to-charge ratio range of m/z 10–3400. The
TSQ Quantiva MS can operate in a mass-to-charge ratio range of m/z 10–1800.
With the TSQ Endura or TSQ Quantiva MS, you can acquire and display mass spectral data
(intensity versus mass-to-charge ratio) in one of two data types:
• Profile data
With profile data, you can see the inherent shape of the peaks in the mass spectrum. The
mass spectrum divides each atomic mass unit into several sampling intervals. The
intensity of the ion current is determined at each sampling interval. The intensity at each
sampling interval is displayed with the intensities connected by a continuous line.
• Centroid data
With centroid data, you can see the mass spectrum as a bar graph. This scan data type
sums the intensities of each set of sampling intervals. This sum is displayed versus the
integral center of mass of the many sampling intervals. Centroid data requires about
one-tenth the computer disk space of what is required for profile data.
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